The Racial Paradox in Multiarterial Conduit Utilization for Coronary Artery Bypass Grafting

Background: It has been established that outcomes for black patients undergoing coronary artery bypass graft surgery (CABG) are inferior to those of their white counterparts. The purpose of this study was to determine (1) whether rates of multiarterial grafting are different among black patients and white patients, and (2) whether racial differences exist in postoperative outcomes after accounting for grafting strategy.

Methods: A retrospective review of black patients (n = 2,810) and white patients (n = 13,569) who underwent isolated, primary CABG from January 2002 to June 2014 at a US academic institution was performed. A modified predicted risk of mortality (M-PROM) score was calculated for each patient using all The Society of Thoracic Surgeons variables for CABG excluding race. Multivariable linear, logistic, and Cox regression analyses were used to assess between-group differences, adjusted for M-PROM.

Results: Overall, 16,379 patients underwent CABG, and 2,441 (14.9%) received more than one arterial graft. When adjusted for M-PROM, the odds of blacks undergoing multiarterial CABG were 10% greater than for whites (p = 0.05). Blacks had worse inhospital outcomes, including higher odds of stroke (odds ratio 2.41, 95% confidence interval [CI]: 1.80 to 3.25) and prolonged intubation (odds ratio 2.01, 95% CI: 1.77 to 2.28). The increase in postoperative complications did not translate to a difference in inhospital mortality (p = 0.10) between racial cohorts. Moreover, among patients who underwent multiarterial grafting strategies, blacks had a hazard of mortality that was 34% higher (95% CI: 22% to 51%)) than that of their white counterparts. Among black patients, those who underwent multiarterial grafting strategies showed better long-term survival than those undergoing single grafting strategies (hazard ratio 0.86, 95% CI: 0.78 to 0.96).

Conclusions: Despite similar rates of arterial grafting for black patients and white patients in this large single-center cohort, black patients continued to have significantly worse late survival when compared with white patients. Continued evaluation as to the causes of this disparity is warranted.